Blit a 9 sliced source bitmap atlas to a target width and height

gistfile1.rb

  # Add to a Sprite object, or derivative
  # Assumes self.bitmap has been set to the desired target width and height
  def blt_9slice(args={})
    args = {
      src_bitmap: nil,
      :frame_width => { # Can also be a number to be used for all corners
        :top_left   => 5,
        :top_right  => :top_left,
        :mid_left   => :top_left,
        :mid_right  => :top_left,
        :btm_left   => :top_left,
        :btm_right  => :top_left
      },
      :frame_height => { # Can also be a number to be used for all corners
        :top_left   => 5,
        :top_right  => :top_left,
        :mid_top    => :top_left,
        :mid_btm    => :top_left,
        :btm_left   => :top_left,
        :btm_right  => :top_left
      }
    }.merge(args)

    # Set src_bitmap for convenience
    src_bitmap = args[:src_bitmap]
    # Set width and height params for each frame / corner
    tl_f_width = tl_f_height = tr_f_width = tr_f_height = ml_f_width = mr_f_width = mt_f_height = mb_f_height = bl_f_width = bl_f_height = br_f_width = br_f_height = 0 

    # Go through hash params and find values or set defaults
    [:top_left, :top_right, :mid_left, :mid_right, :mid_top, :mid_btm, :btm_left, :btm_right].each do |frame|
      if args[:frame_width].is_a? Numeric
        width = args[:frame_width]
      else
        width = args[:frame_width][frame]
        # Reference other arg value if symbols
        width = args[:frame_width][width] if width.is_a? Symbol
        # If no value, set default to top left
        width = args[:frame_width][:top_left] unless width
      end

      if args[:frame_height].is_a? Numeric
        height = args[:frame_height]
      else
        height = args[:frame_height][frame]
        # Reference other arg value if symbols
        height = args[:frame_height][height] if height.is_a? Symbol
        # If no value, set default to top left
        height = args[:frame_height][:top_left] unless height
      end

      case frame
      when :top_left
        tl_f_width  = width
        tl_f_height = height
      when :top_right
        tr_f_width  = width
        tr_f_height = height
      when :mid_left
        ml_f_width  = width
      when :mid_right
        mr_f_width  = width
      when :mid_top
        mt_f_height = height
      when :mid_btm
        mb_f_height = height
      when :btm_left
        bl_f_width  = width
        bl_f_height = height
      when :btm_right
        br_f_width  = width
        br_f_height = height
      end
    end

    # Rects for copying sections of src_bitmap
    # Top
    tl_frame = Rect.new(0, 0, tl_f_width, tl_f_height)
    t_frame   = Rect.new(tl_f_width, 0, src_bitmap.width - (tl_f_width + tr_f_width), mt_f_height)
    tr_frame = Rect.new(src_bitmap.width - tr_f_width, 0, tr_f_width, tr_f_height)

    # Middle
    ml_frame  = Rect.new(0, tl_f_height, ml_f_width, src_bitmap.height - (tl_f_height + bl_f_height))
    m_bg      = Rect.new(ml_frame.width, ml_frame.y, src_bitmap.width - (ml_f_width + mr_f_width), ml_frame.height)
    mr_frame  = Rect.new(src_bitmap.width - mr_f_width, tr_f_height, mr_f_width, ml_frame.height)

    # Bottom
    bl_frame = Rect.new(0, src_bitmap.height - bl_f_height, bl_f_width, bl_f_height)
    b_frame   = Rect.new(bl_f_width, src_bitmap.height - mb_f_height, src_bitmap.width - (bl_f_width + br_f_width), mb_f_height)
    br_frame = Rect.new(src_bitmap.width - br_f_width, src_bitmap.height - br_f_height, br_f_width, br_f_height)

    # Diffs
    width_diff  = (self.width.to_f / m_bg.width).ceil
    height_diff = (self.height.to_f / m_bg.height).ceil

    # First blt fill
    fill_width = self.width - (ml_f_width + mr_f_width)
    fill_height = self.height - (mt_f_height + mb_f_height) 
    m_bg_width = m_bg.width
    m_bg_height = m_bg.height
    width_diff.times do |hn|
      total_width = m_bg.width * (hn+1)
      m_bg.width -= total_width - fill_width if total_width > fill_width
      m_bg.height = m_bg_height # Reset on horizontal pass
      height_diff.times do |vn|
        total_height = m_bg.height * (vn+1)
        m_bg.height -= total_height - fill_height if total_height > fill_height
        self.bitmap.blt(tl_f_width + (m_bg_width * hn), tl_f_height + (m_bg_height * vn), src_bitmap, m_bg)
      end
    end

    # Top left frame
    self.bitmap.blt(0, 0, src_bitmap, tl_frame)
    # Top frame
    mid_width = self.width - (tl_f_width + tr_f_width)
    t_frame_width = t_frame.width
    width_diff.times do |n|
      total_width = t_frame.width * (n+1)
      t_frame.width -= total_width - mid_width if total_width > mid_width
      self.bitmap.blt(tl_f_width + (t_frame_width * n), 0, src_bitmap, t_frame)
    end
    # Top right frame
    self.bitmap.blt(self.width - tr_frame.width, tr_frame.y, src_bitmap, tr_frame)

    # Mid left frame
    mid_height = self.height - (tl_f_height + bl_f_height)
    ml_frame_height = ml_frame.height
    height_diff.times do |n|
      total_height = ml_frame.height * (n+1)
      ml_frame.height -= total_height - mid_height if total_height > mid_height
      self.bitmap.blt(0, tl_f_height + (ml_frame_height * n), src_bitmap, ml_frame)
    end
    
    # Mid right frame
    mid_height = self.height - (tr_f_height + br_f_height)
    mr_frame_height = mr_frame.height
    height_diff.times do |n|
      total_height = mr_frame.height * (n+1)
      mr_frame.height -= total_height - fill_height if total_height > fill_height
      self.bitmap.blt(self.width - mr_frame.width, tr_f_height + (mr_frame_height * n), src_bitmap, mr_frame)
    end

    # Bottom left frame
    self.bitmap.blt(0, self.height - bl_f_height, src_bitmap, bl_frame)
    # Bottom frame
    mid_width = self.width - (bl_f_width + br_f_width)
    b_frame_width = b_frame.width
    width_diff.times do |n|
      total_width = b_frame.width * (n+1)
      b_frame.width -= total_width - mid_width if total_width > mid_width
      self.bitmap.blt(bl_f_width + (b_frame_width * n), self.height - b_frame.height, src_bitmap, b_frame)
    end
    # Bottom right frame
    self.bitmap.blt(self.width - br_frame.width, self.height - br_frame.height, src_bitmap, br_frame)
  end